This invention relates in general to vehicle disc brake assemblies and in particular to a guide pin isolation damper adapted for use in such a vehicle disc brake assembly.
Most vehicles are equipped with a brake system for slowing or stopping movement of the vehicle in a controlled manner. A typical brake system for an automobile or light truck includes a disc brake assembly for each of the front wheels and either a drum brake assembly or a disc brake assembly for each of the rear wheels. The brake assemblies are actuated by hydraulic or pneumatic pressure generated when an operator of the vehicle depresses a brake pedal. The structures of these drum brake assemblies and disc brake assemblies, as well as the actuators therefor, are well known in the art.
Typical disc brake assemblies include a rotor which is secured to the wheel of the vehicle for rotation therewith. The rotor includes a pair of opposed friction plates which are selectively engaged by portions of a caliper assembly. The caliper is slidably supported on an anchor bracket by guide pins. The guide pins are secured to the caliper by guide pin fasteners and extend into bores of the anchor brackets. The guide pins contact the anchor bracket at contact points in the bores and create a contact load on each of the guide pins at the contact points.
The anchor bracket is attached to a non-rotatable component of the vehicle, such as the vehicle frame. The caliper assembly includes a pair of brake shoes which are disposed on opposite sides of the brake rotor. The brake shoes are connected to one or more hydraulically or pneumatically actuated pistons for movement between a non-braking position, wherein they are spaced apart from the opposed friction plates of the rotor, and a braking position, wherein they are moved into frictional engagement with the opposed friction plates of the rotor. When the operator of the vehicle depresses the brake pedal, the piston urges the brake shoes from the non-braking position to the braking position so as to frictionally engage the friction plates of the rotor and thereby slow or stop the rotation of the associated wheel of the vehicle.
The anchor bracket bores have a greater diameter than the guide pins. The guide pins have a clearance between an exterior surface of the guide pin and an interior surface of the bore such that the guide pins may move within the bores. As disclosed in U.S. Patent Publication No. 2014/0116817 to Morais et al., the disclosure of which is incorporated herein by reference in entirety, a damper may be provided on the guide pins to provide a defined point of contact between the guide pins and bores when a brake loading is applied to the disc brake assembly. However, a guide pin with a defined contact point may still contact or strike the interior surface of the bore and produce noise, vibration, or harshness when there is no brake loading or a low pressure brake loading. Thus, it would be desirable to reduce or control metal on metal contact between the guide pins and the interior surface of the bores.